The present invention relates in general to motor vehicle entry and security systems, and, more specifically, to activation of a welcoming function such as courtesy lighting when a user approaches a vehicle.
The use of various different types of wireless technologies has made many advanced remote-control and security functions available for users of motor vehicles. In a remote keyless entry (RKE) system, for example, a portable key fob carried by the user includes a button-activated transmitter for sending commands to a vehicle-mounted receiver for unlocking doors, starting of the vehicle engine, and other functions. Remote entry and remote start systems typically operate in the UHF frequency band and provide a significant range, typically up to several tens of meters for standard systems, and for higher end systems, typically up to 150 meters.
In contrast with RKE systems which require a user to press a button on a key fob, passive systems have been developed wherein no direct user interaction with the remote device is necessary. In response to detecting a manipulation of the vehicle by the user, or entering a certain zone around the vehicle, the vehicle runs a check for the presence of the key fob or other wireless device in the user's possession in order to validate the user's identity. In the case of passive entry, when the user touches a door handle of a locked vehicle, the vehicle activates a short range, low frequency (LF) transmitter to send an LF challenge signal in the area around the door. Some OEMs may activate the short range challenge when the key fob is detected in a specified zone around the vehicle. The LF challenge signal is detected by the user's remote device which then wakes up and sends an authentication signal to the vehicle (typically using a UHF channel, but other communication channels can also be used). For passive engine start, a start button provided in the vehicle interior is pressed by the user in order to initiate a similar LF challenge and UHF response detection and authentication that the user's portable device is in the area of the driver seat. In this way, use of a mechanical key and the need for manual activation of fob buttons by the user can be eliminated for daily use and reserved just as a back-up. For maximum convenience, the passive entry/passive start functions may be integrated in an RKE fob, thereby providing great convenience and flexibility of use.
Another wireless technology being increasingly adopted in motor vehicles involves the installation of a cellular phone modem. Voice and data communications over the cellular telephone system allow various services such as remote unlocking, vehicle location, navigation assistance, and many other functions. Smart phone applications are being developed allowing a mobile phone device to be used to remotely control various systems in a vehicle.
Modern vehicles are also being made with various types of wireless networking capabilities, such as Bluetooth, Bluetooth Low Energy, and WiFi networks allowing a vehicle to interact with various other electronic devices carried by a user such as a smart phone, tablet, netbook, or a media player.
When an unattended vehicle is left in a parked condition, any active electronic systems create a battery drain that could eventually result in insufficient energy to start the vehicle engine when the user returns. Therefore, the quiescent current used by any active systems must be low. The manufacturer typically sets a maximum key-off load (KOL) for a particular vehicle design in order to avoid battery drain issues for a minimum period of 30 days after receipt by a customer, but sometimes up to 60 days for certain customer segments.
For some wireless communication systems such as an RKE receiver and a cellular modem, sufficiently low quiescent currents are achievable. For other systems such as LF-based passive entry systems, Bluetooth systems, and WiFi systems, power consumption is too high to allow any significant operation times when the engine is not running. Because of these power management issues, passive entry systems typically do not scan for the presence of a user until the occurrence of a user initiated action such as touching a door handle. This allows the passive entry feature to be available for the full 30 day period.
A highly desired convenience feature associated with unlocking and/or entry into a vehicle is comprised of a welcoming function which “greets” the user. The welcoming function typically includes the activation of vehicle interior and exterior lighting including puddle lights, front and rear running lamps, cabin courtesy lights, and the playing of a sound such as a horn chirp. The welcoming function may also include adjustment of various personalization features in the vehicle such as the automatic placement of power seats so that the vehicle is ready and completely personalized for the approaching user upon entry to the vehicle. In conventional systems, however, the welcoming function is typically only initiated once a user activity has been detected such as pressing an unlock button on the key fob or touching the door handle during passive entry. It would be desirable to initiate a welcoming function as a result of the user merely approaching within a short distance of the vehicle without requiring a button press or an interaction with the vehicle. For example, if not initiated until the user has touched a door handle, a seat movement into a corresponding personalization position may not be completed by the time the user wishes to enter the seat. In addition, there are personal security benefits to the user from the activation of exterior and interior lighting prior to the moment that the door handle is contacted. On the other hand, activation of the welcoming functions at too great of a range may result in false activations when the user is nearby but is not in fact approaching or about to use the vehicle.
One possible approach would be to detect user presence within a short range of the vehicle without requiring touching of the vehicle by continuously operating the LF transmitter of a passive entry/passive start (PEPS) system. Since localization of the user to a particular door or trunk area would not be required, a specific antenna and power configuration of the LF transmitter would be provided to create a desired detection region around the vehicle (such as an area within about 3 to 5 meters). Although the welcoming function could then be activated in the appropriate circumstances, the battery drain resulting from excessive LF transmitter operation is prohibitive. The action of continuously checking for the approach of the user and their remote device, result in high vehicle battery power consumption which cannot be allowed for the full 30 days of target parking life. As such, this method of proximity detection typically only allows the detection feature to be active for around 5 to 10 days from the last drive cycle.
Another possibility for welcoming function activation would be to provide communication between the vehicle and a smart phone carried by the user, so that the relative positions between the vehicle and the user/phone can be detected and analyzed. For example, the vehicle parked position could be obtained from a GPS receiver in the vehicle or in the phone at the vehicle key-off event which is then stored by the phone. After exiting the vehicle, the phone could monitor the relative distance between the vehicle and phone to detect whether the user has moved away and then returned within a predetermined distance of the vehicle, at which point the phone would initiate communication with the vehicle. Although vehicle battery drain would be acceptable in this method, the battery usage by the phone would be higher and the combination of phone communication and GPS positioning would be unreliable and not achieve the desired performance. For example, GPS signals are not receivable in all areas, such as parking structures, or accurately in areas with tall buildings. In addition, once a smart phone has detected that the user has moved into a position requiring activation of the welcoming function, the time delay or latency involved in establishing a cellular connection from the phone to the vehicle may introduce a lag that defeats operation of the welcoming function. Further, the tolerances of GPS (typically 3 to 6 meters) relative to both the position of the phone and the position of the vehicle, create a large error zone where activation may be initiated by overlap of the GPS zones but not truly intended by the user. This may result in excessive unwanted wake-up of the vehicle resulting in higher vehicle battery power consumption and frustration by the user due to vehicle illumination without an intended or deliberate request.
Short range wireless networks such as Bluetooth and WiFi networks are also not a good choice for initiating a welcoming function. A typical operating range for Bluetooth and WiFi would typically be too large for use in detecting entry into a small detection region around the vehicle. Moreover, battery drain from either Bluetooth or WiFi hardware would exceed KOL limits. Use of Bluetooth Low Energy could reduce the vehicle side power consumption for the Bluetooth LE transceiver; however, less than a majority of phones have or may have Bluetooth LE for the foreseeable future making it difficult to build a strategy around Bluetooth LE.